ireland nicole, you can go either way on it. Either do the labs first, or try it on your own and see. Trying it on your own first is cheaper.
Also, most DANS will want you to do that, first thing, anyway, even before they've done any labs. I went ahead and took Justin gf/cf before the first DAN appt. Actually, I was in process of taking him gf/cf, I did it gradually not cold turkey, so he wasn't 100% but getting close.
The way I did it was to start replacing products as we ran out of something. When we ran out of milk, I bought rice milk. When we ran out of cereal, I bought gf cereal. I did buy some stuff up-front like rice flour (since it would take me quite a while to run out of real flour) but most of it got replaced one thing at a time.
Another thing I did, might not be necessary for everyone but worked for us, some of the foods I did a week's "break" when I converted over. For example, the cheese. We had regular cheese, then ran out. And then went for a week without
any cheese in the house, before introducing the new cheese. DS was so happy to get cheese, apparantly he forgot what it tasted like. I also made a point to buy some extra yummies those weeks, food that was safe but were treats. Then it didn't seem like such torture.
Some people knock out the dairy first, because it's the easiest, then start on the gluten. We kinda did both at once. There's also a learning curve for Mom to get used to how to cook that way (cause rice flour doesn't
act like regular flour and rice milk doesn't act like cow's milk). There are also some prepared foods and mixes that are awful, like there's a macaroni and
chreese mix that is nasty nasty nasty. We tried 4 or 5 different pizza crust mixes before I found the one DS liked. I used to only make bread machine bread but lately have been buying it pre-made, it's more expensive but less hassle, however if you like to bake you might really like making the bread yourself. But one thing at a time, your kid probably is self-limiting with food anyway?, and you just have to come up with stuff to replace what he likes now, you don't need to start manufacturing 4-course dinners.
If you go completely dairy-free and your kid doesn't do veggies, you'll probably want a calcium supplement.
The gfcfdiet.com website has a directory of safe foods. If you go to the bottom of the front page (where they're trying to sell you stuff) and go to the "index" or "directory" I think it says, there is a huge huge listing. Some school supplies also have gluten, so I printed those pages out to take to the teacher.